DISTINCT NEUROTROPHIC RESPONSES OF AXOTOMIZED MOTOR-NEURONS TO BDNF AND CNTF IN ADULT-RATS

IN adult mammals, transection of the hypoglossal nerve results in a dramatic loss of choline acetyltransferase (ChAT) in the hypoglossal motor neurons without affecting their cell number. This injury-induced reduction in ChAT is prevented when brain-derived neurotrophic factor (BDNF) is applied to the proximal end of the transected nerve. In contrast, application of ciliary neurotrophic factor (CNTF) has no such effect, even though both factors are known to rescue developing motor neurons from cell death. These results suggest that BDNF may regulate the phenotypic expression of ChAT in mature motor neurons, and indicate that the sensitivity and response of motor neurons to such neurotrophic agents change with development.